A great number of underground engineering projects such as high building foundation reinforcement, foundation pit excavation, bridge erection, express way roadbed reinforcement, etc. need to be reinforced at a foundation by grouting. In the prior art, the cement slurry at the construction site needs to be brought back to a laboratory to be detected, and a core sample needs to be extracted on site when the cement soil density is detected, so that the detection means is complex, the period is relatively long, and the problem such as the existence of cheating on workmanship and materials is difficult to determine rapidly. For the fact that the construction of the underground engineering has certain concealment, a construction unit may cheat on workmanship and materials for its own benefit when in operation, which brings great safety potential hazard to the infrastructure in China. Therefore, there is an urgent need for a technical means to detect a cement admixing amount in real time at the construction site.